Mowsky



UNITED STATES PATENT tries.

ERIVIN F. VON \VILMOVVSKY, OF BOSTON, MASSACHUSETTS, ASSIGNOR OF ONE-HALF TO IVALTER D. EDMONDS, OF NEIV YORK, N. Y.

FILAMENT FOR INCANDESCENT LAMPS.

SPECIFICATION forming part of Letters Patent No. 597,172, dated January 11, 1898. Application filed September 3,1896. Serial No. 604,802. on model.)

To aZZ whom it may concern: a solid compound of magnesium and boron Be it known that I, ERWIN F. VON VVIL- by subjecting amorphous boron or the com MOWsKY, a citizen of the United States, repounds of boron to the action of metallic siding at the city of Boston, Commonwealth magnesium at the high temperature of, say, 5 of Massachusetts, have invented a new and a yellow heat, in an atmosphere of hydrogen useful article of manufactureto wit, a new or other equivalent gas, preferably under electrical conductor for use in incandescent higher than normal atmospheric pressure,and electric lighting, and also means or methods in the proportion of, say, one part of preferof producing the same, of which the following ably amorphous boron to three and one-half I0 is a specification. V parts of magnesium. The resulting mixture The objects of my invention are to produce or compound, containing mainly magnesium an electrical conductor for use in incandesand boron, is a solid which should be stored cent electric lighting which shall consist in for use in Well-stoppered vessels until rewhole or mainly, but not necessarily entirely, quired in a subsequent step of the process, r 5 of a material of very high infusibility and as hereinafter described. From this comresultant electric-current-carrying and lightpound or mixture of boron and magnesium, radiating capacity, and likewise to devise and possibly hydrogen, I produce a gas by suitable means and methods of producing decomposing it by means of any convenient said material and. for its incorporation into a acidsuch, for instance, as muriatic or acetic 7o 20 practical incandescent conductor. The inacid or the like-and taking care to avoid any fusibility of said material is quite beyond the oxidizing acid-such, for instance, as nitric temperature at which the most refractory acid. In practice the gas desired may be metals melt. produced by depositing the solid compound,

I attain the objects of my invention by conbroken into convenient pieces, in a glass ves- 2 5 structin g my electrical conductor in whole or sel or retort from which atmospheric air has mainly, but not necessarily entirely, (since, been completely displaced by a gas, such as for instance, some other material, such as carhydrogen. The acid may then be applied in bon, may formacore and be incidentally part any convenient manner and in proportion of the filament, as hereinafter more fully reto the supply of gas which it is desired shall 3o ferred to,) of boron and applying it for use, be produced. It is also prudent to apply preparing the boron, and incorporating it into to the exterior of the glass vessel any of the such electrical conductor as follows: Boron well-known cooling appliances. The maghas hitherto been known only in the form of nesium of the above solid compound coma powder and not in any such form as adbines with the acid and remains behind, to- 35 mitted of its application and use for the purgether with the greater part of the boron, pose of electric incandescent lighting. I have while a gas mixture containing, essentially, invented an'electrieal conductor composed hydrogen and a boron compound is develsubstantiallyof boron brought into form and oped. Said boron compound is characterized condition available for the purposes of eonby its quality of becoming decomposed when 4o ductors for electric incandescent lighting by brought into contact with hot surfacesfor means of treatment which I have invented instance, those of a carbon filament at or and which I will hereinafter describe. above red heatin which case the boron will Broadlyconsidered,myinventiontherefore be deposited upon such surfaces in an eleccnsists in the construction of an electrical mentary condition and in more or less dense 5 45 conductor forincandescent lighting substanform, so as to adhere. The gas resulting tially composed of boron and in the producfrom the decomposition of the solid compound tion of amethod of treating this hitherto unor mixture, containing mainly boron and available substance in such manner as to enmagnesium, as aforesaid, and which I will able it to be used for the purpose desired. hereinafter term boron gas, should be 50 My boron electrical conductor may be pref- Washed with water and be dried-for instance, erably constructed as follows: I first prepare by sulfuric acid-in the well-known manner.

It is then ready for application, as hereinafter described. I also prepare by inclosin gin a convenient chamber or vessel a core in an electric circuit, said core having the form or arrangement which is desired in the electrical conductor to be constructed. Such core may consist of a very thin iron wire or, preferably, athin electrical conductor of carbon. The atmosphere is carefully removed from the interior of the chamber or vessel containing this electrical conducting -core and hydrogen or its equivalent substituted therefor. The gasometer or other vessel containing the dry gas derived from the compound or mixture of magnesium and boron is then connected with the interior of the chamber or vessel containing the aforesaid core, and said gas admitted and preferably carried through in a continuous stream under sufficient pressure to expel the hydrogen or its equivalent through a tube dipping into sulfuric acid, whereby the said gas containing the boron is caused to surround the said core. The electric current is now passed through the said core, so as to heat the same at or above red heat and thereby decompose the boron gas and to deposit boron upon the surface of the heated core, care being taken to keep the temperature of the growing electrical conductor as constant as possible by regulating the current. Under the conditions described the boron in the said gas will be evenly deposited upon all sides of the said core, and the thickness of the deposit will depend upon the length of the exposure. The exposure may be continued until the deposited boron shall constitute altogether the major portion of the resulting electrical conductor, the core being comparatively so small and insignificant as to be substantially disregarded, not only as regards relative bulk, but also electrical function. In the application of the process as described care should be taken to exclude silicon in every form at all stages of the procedure, since the presence of silicon or its compounds in even the slightest amount in the incandescent conductor is likely to discolor the glass bulb into which the electrical conductor as finally constructed is to be mounted for use in the usual Way.

The thickness of the deposit of the boron upon the core should be such as to insure sufficient mass in the boron to enable it to resist the disturbances which may be caused by the contraction and expansion of the core, since the coefficient of expansion of the carbon or metallic core is different from that of the boron,and unless the deposithas been continued to an extent to insureindependent strength in the mass of boron the latter is likely to be broken and to peel undesirably in consequence of changes of temperature in the core. It will be understood that the core plays substantially no function in the operation of the completed electrical conductor, its use being primarily and principally to afford only a nucleus or support upon which the deposit may be commenced. It is likewise of importance to the successful application of my process that too high temperature should be avoided during the deposit of the boron. A temperature should be found and adhered to with the greatest possible constancy during the deposition, which, while generally describable, as aforesaid, as at or above red heat, will not be so high as to result in the undue agglomeration of the depositing boron, whereby an undesirable tendency of the mass to crack and peel is developed, but should, on the contrary, be of such comparatively lower temperature as to insure a sufficiently loose contact between the particles of depositing boron,among themselves,and also between them and the carbon core to prevent slight possible variations in the temperature of the core from rupturing the mass of the deposit prior to the latter having gain ed sufficient bulk to be selfsupporting and able to resist such variations. As the deposition progresses, however, the temperature should be raised successively to correspondingly increase the compactness and strength of the deposit then being added. It is of advantage to have comparatively loosely compacted those particles of boron in the immediate vicinity of thecore to insure greater elasticity, and-consequently diminished liability to fracture and peel, and to have all the rest of the boron more densely compacted, so as to increase the strength of the electrical conductor as a whole. The density of the deposit or. the compactness of the particles of the boron in different portions of the electrical conductorthat is to say, the comparative looseness of the deposit at the interior or at its interior layers as compared with its comparative density at the exterior. layerswill also depend upon the concentration of the boron gasnamely, the quantity of boron contained in the unit volume-and such relative density may be regulated accordingly during the progress of deposition-that is to say, the density of the boron deposited is inversely proportional to the rapidity of the deposition and the rapidity of the deposition is proportional to the concentration of the boron gas. Thus if at the commencement-of the deposition the deposition-chamber be completely filled with the gas containing boron deposition will take place more rapidly and the particles of the deposit will be less tightly compacted together. As the deposition continues and the point is reached in which the comparative looseness of the particles ceases to be desirable, and greater compactness is of advantage, the concentration of the boron gas may be diminished by dilution with hydrogen or its equivalent, in consequence of which the speed of the deposition will be proportionately delayed and the compactness of the particles toward the exterior of the electrical conductor proportionately increased, with the resulting advantages which have already been described.

Though I have referred to metallic magnesium as utilized in the production of my boron gas, I do not Wish to be understood as confining myself to that particular metal. It will of course be understood that similar easilyoxidizable metals might be employed, the boron compounds of which are readily decomposable by acids, producing gases, as aforesaid. The proportions of ingredients which I have mentionedwill also doubtless somewhat var according to each particular case, Without departing from my invention, since it is impossible to prescribe exact quantities and proportions for all conditions, and these should be studied and dealt with as experience in each case shall demonstrate.

The compound or mixture of magnesium and boron is preferably made by filling an iron crucible capable of withstanding pressure with solid pieces of magnesium metal embedded in the amorphous boron, and this in such a way that the charge is separated from the iron by a layer of anhydrous magnesia. Care, however, should be taken to heat all parts of the crucible uniformly and not to continue the heat too long after the reaction has talcenplace, else the compound will be decomposed by the magnesium volatilizing in the upper, because usually cooler, part of the crucible, while the boron remains in the lower part.

The boron deposited by my method, de-.

scribed as aforesaid, will be substantially pure, homogeneous, and adhesive.

hat I claim as new, and desire to secure by Letters Patent, is the following, viz:

1. A filament or conductor for incandescent lighting composed substantially of boron.

2. An electrical conductor for use in incandescent electric lighting, composed of substantiallypure, homogeneous and adhesive boron.

3. An electrical conductor for use in incandescent electric lighting consisting of a continuous body of pure homogeneous and adhesive boron, substantially as and for the purposes described.

4:. An electrical conductor for use in incandescent electric lighting, consisting of a coniin nous annular deposit of substantially pure, homogeneous and adhesive boron around a central core of electrically-conducting material, substantially as and for the purposes de scribed.

5. The method of making an incandescent filament or conductor com posed substantially of boron, which consists in producing a compound or mixture mainly of magnesium and boron, or boron compounds, decomposing the same into a gas containing boron, and cansing the deposition from the said gas of a conductor composed substantially of boron.

6. The method of making an incandescent filamentor conductor composed'substa-ntially of boron, which consists in producing a com pound or mixture mainly of magnesium and boron, or boron compounds, decomposing the same into a gas containing boron, and causing the deposition from the said gas of a conductor composed substantially of boron through the heating action of an electric current.

'7. An electrical conductor for use inincandescent electric lighting, consisting of an annular continuous deposit of boron around a central electrically-conducting core, the particles of the boron being at or near such core less compacted than at or about the exterior of said conductor, substantially as and for the purposes described.

8. The method of producing an electrical conductor for use in incandescent electric lighting, composed of a continuous deposit of boron which consists in producing a solid compound or mixture mainly of magnesium and boron, decomposing the same into a gas containing boron, and heating by the electric current a core in the presence of said gas containing boron, substantially as and for the purposes described.

9. The process of producing an electrical conductor for use in incandescent electric lighting, consistingof a continuous deposit of boron, the particles of which are less compacted toward the interior and more compacted toward the exterior, which consists in preparing a com pound or mixture mainly of magnesium and boron, decomposing the same into a gas containing boron, and heating in the presence of such gas a core, the said heating being at the outset of the operation at a lower temperature than at the close of such operation, substantially as and for the purposes described.

10. The process of constructing an electrical conductor for use in incandescent electric lighting, composed of a continuous deposit of boron, which consists in producing a solid compound mainly of boron, and magnesium, by subjecting said boron or its compounds and metallic magnesium to a high tempera-v ture in the presence of hydrogen, decomposing said compound by acid treatment into a gas containing boron, and heating a core in the presence of said last-mentioned gas by an electrical current, all substantially as and for the purposes described.

11. The process of constructing an electrical conductor for use in incandescent electric lighting, composed of a continuous deposit of boron, which consists in producing under pressure a solid compound mainly of boron and magnesium, by subjecting said boron or its compounds and metallic magnesium to a high temperature in the presence of hydrogen, decomposing said compound by acid treatment into a gas containing boron, and heating a core in the presence of said lastmentioned gas by an electrical current, all substantially as and for the purposes described.

12. The method of making an incandescent filament or conductor composed substantially of boron, which consists in producing a IIllX- ture or compound mainly of magnesium and boron or boron compounds by heating the said materials in the presence of a non-oxidizing gas, then decomposing this compound prodnot in the absence of the atmosphere by anonoxidizing acid into a gas containing boron, and causing said gas to deposit a conductor of boron, or a compound containing boron, through the action of an electric current.

13. The method of making an incandescent filament or conductor composed substantially of boron, which consists in producing a mixture or compound mainly of magnesium and boron or boron compounds by highly heating the said materials in the presence of hydrogen, then in the absence of the atmosphere decomposing this compound product by muriatic or acetic acid, into a gas containing boron, and causing said gas to deposit a conductor of boron, or a compound containing boron, through the action of an electric current.

14. The process of constructing an electrical conductor, for use in incandescent electric lighting, composed of a continuous deposit of boron, which consists in producing a solid compound of boron and some suitable easily-oxidizable metal such as magnesi um,by subjecting said boron or its compounds and such metalto a high temperature in the presence of hydrogemdecomposing said compound by acid treatment into a gas containingboron,

and heating a core in the presence of said last-mentioned gas by an electrical current,

all substantially as and for the purposes described.

15. The method of making an incandescent filament or conductor composed substantially of boron, which consists in producing a mixture or compound mainly of magnesium and boron or boron compounds by heating the said materials under pressure in the presence of a non-oxidizing gas, and then decomposing this compound product in the absence of the atmosphere by a non-oxidizing acid, into a gas containing boron, and causing said gas to deposit an adhesive conductor of boron or a compound containing boron through the action of an electric current.

16. The method of making an incandescent filament or conductor composed substantially of boron, which consists in producing a mixture or compound mainly of magnesium and boron or boron compounds by highly heating the said materials under pressure in the presence of hydrogen, then in the absence of the atmosphere decomposing this compound product by inuriatic or acetic acid into a gas containing boron, and causing said gas to deposit an adhesive conductor of boron, or a compound containing boron, through the action of an electric current.

Dated New York, September 1, 1896.

ERWIN F. VON \VILMOWSKY. Witnesses:

T. C. BYRNES, FRANCIS WHITE PROSCHER. 

